The Future of Reindeer at Risk

Image: male woodland caribou standing in a snow covered spruce forest.

Reindeer, Rangifer tarandus, known as caribou in North America, are an Ice Age survivor and the only member of the deer family that thrives year-round in the Arctic. Over thousands of years, they’ve evolved a remarkable set of adaptations including physical, behavioural, and physiological traits that allow them to withstand extreme cold. Beyond their ecological role in balancing tundra systems, reindeer also carry deep cultural and economic significance for many Indigenous Peoples.

Even though they remain the Arctic’s most numerous herbivore, their populations have been shrinking at an alarming pace. Over the past thirty years, global warming and its indirect impacts have driven a dramatic decline, with estimates suggesting that close to two-thirds of reindeer have vanished during that period.

Growing concern surrounds the future of reindeer as additional pressures mount. Expanding human activity and land-use changes are fragmenting their habitats, putting stress on both wild herds and semi-domesticated groups. Their decline is more than a conservation issue, it also threatens the food security and cultural traditions of Indigenous communities.

An international team of researchers from the University of Adelaide and the University of Copenhagen, co-led by Associate Professor Damien Fordham, Environment Institute Deputy Director, sought to understand how reindeer have responded to past environmental change to better predict their chances in a warming future.

To do this, they combined evidence from fossils, ancient DNA, and advanced computer simulations to trace changes in both abundance and range. Their analysis stretched back some 21,000 years, allowing them to compare historical population trends against scenarios for the decades ahead.

“This revealed that populations of reindeer have experienced major declines during periods of rapid climate warming, but the losses expected in the coming decades due to future climate change are likely to be even more severe than those in the past,” says Professor Fordham.

The team’s models show that herds in North America are especially vulnerable, with forecasts indicating that numbers could plummet by more than 80% before the end of this century. Still, Fordham emphasises that the trajectory is not fixed: cutting greenhouse gas emissions substantially, alongside stronger investment in conservation strategies, could prevent the worst outcomes.

“These declines are likely to have far-reaching ecological implications that will further increase the vulnerability of caribou in North America and reindeer in Eurasia to climatic warming and other stressors.”

One major concern is the ripple effect on plant diversity. Reindeer strongly influence tundra ecosystems by grazing selectively, which shapes plant growth and maintains biodiversity. Without them, entire plant communities risk collapsing, with a domino effect reaching even into carbon storage. The absence of reindeer could accelerate the release of stored carbon from Arctic soils, deepening climate challenges.

“Increasing investment in the management and conservation of reindeer and caribou populations, particularly in North America, where losses are forecast to be greatest, will benefit the persistence of this species and the services it provides to Arctic ecosystems and the communities that depend on them,” says Associate Professor Fordham.

The full study is available in Science Advances.